1966 buick gs fuel tank

[geo3280]

hello everyone I was wondering if anyone knows if a fuel tank from a 1965 gs would interchange with my 66 gs they appear to be same dementions but mine is 20 gal 65 is 21.5

[TODD]

Buick Parts book shows all 64-66 A bodies (except wagons) use the same tank. Part number is 1377756. The shop manuals for these years all show a rated fuel capacity of 20 gallons.

I see where Rock Auto calls these 21.5 gal tanks. Don't know where that comes from unless they will hold that much when fully topped off.